Final answer:
Imagining an aggressive person as a clown involves symbolic imagery theory, a psychological tactic acting as a defense mechanism to manage anxiety by transforming threatening figures into non-threatening symbols.
Step-by-step explanation:
Imagining an aggressive person as a clown is a mental exercise that draws upon symbolic imagery theory. This theory is concerned with how we mentally transform and represent frightening or threatening concepts into less threatening symbols, such as picturing a scary individual as something as benign and non-threatening as a clown. This psychological tactic could be described as a type of defense mechanism in which mental imagery serves as a way to displace the fear associated with the aggressive individual to manage one's anxiety.
While dual coding theory and cognitive theory also involve mental imagery, dual coding theory refers to the process of coding information using both visual and verbal representations, and cognitive theory deals with our mental processes more broadly. Mental imagery theory would be related as well since it delves into the visualization aspect, but it does not specifically focus on the symbolic transformation of threatening figures into non-threatening ones like the symbolic imagery theory does.